Quantification of road dust transfer to central lane bus stop from other lanes using tire tread rubber markers of bus and passenger vehicle through pyrolytic technique

Abstract

Tire wear particles (TWPs) and road wear particles (RWPs) are produced by friction between the road surface and tire tread, and they mainly consist of road dust. The road dust can be scattered to other places by traffic. In this study, the amount of road dust that can be transferred to central land bus stops from other lanes was investigated by analyzing specific rubber markers of bus and passenger car tire treads using pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) equipped with a Curie point pyrolyzer. The main rubber components of bus and passenger car tire tread rubber compounds are natural rubber (NR) and styrene-butadiene rubber (SBR), respectively. Dipentene, 4-vinylcyclohexene (4-VCH), and 4-phenylcyclohexene (4-PCH) were used as the markers for quantification of NR, BR, and SBR in the sample, respectively. The types and contents of TWPs in the road dust samples collected from uphill and downhill bus stops were examined to determine the degree of road dust transfer. The TWP content in the road dust sample collected from the uphill bus stop decreased from 3.7% to 0.3% as the particle size increased from ≤ 20 μm to 106–212 μm, while that in the road dust sample collected from the downhill bus stop decreased from 1.6% to 0.4% as the particle size increased from 20–38 μm to 106–212 μm. The average TWP content of road dust at the uphill bus stop was higher than that at the downhill bus stop. The inflow rates of road dust from other lanes varied with the particle size. For the road dust of 20–212 μm, the inflow rates of road dust were 27–60% and 49–60% for the uphill and downhill bus stops, respectively. The inflow rate of road dust tended to increase with decreasing the particle size.